A radio test system generally comprises a configuration of test equipment used for measuring the performance parameters of an individual radio, of a radio system, or of any desired sub-system thereof Radio test sets are the primary equipment utilized in radio servicing and are also commonly referred to as "Service Monitors" and/or "Communications Systems Analyzers". In general, radio test systems are routinely used in the manufacture, calibration, repair, installation and general servicing of radios and radio systems both for the purpose of evaluating the performance of the radio or radio system and as a general purpose diagnostic tool to aid in the repair and/or adjustment of a broken or mis-aligned radio, radio system or any constituent sub-system or component of the radio or radio system.
With the advent of progressively more complex radio systems there has been a rapid divergence away from the simple amplitude modulation (AM) and frequency modulation (FM) technologies which were the standard modulation techniques in prior radio systems. More advanced radio systems make extensive use of digital signal processing to improve their spectral efficiency and to decrease the cost of the radio service provided to the user of the radio. The inclusion of digital signal processing permits use of more spectrally efficient modulation technologies such as Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Quadrature Phase Shift Keying (QPSK) and Quadrature Amplitude Modulation (QAM) techniques. These and other present day modulation techniques are fundamentally digital in nature, transmitting information as a digital bit stream, which is received and decoded as digital words by the radio receiver.
As a consequence of this technological evolution, radio tests systems must have increasing capability and flexibility, especially the ability to handle many different modulation and signal coding techniques over a wide range of frequencies and signal levels. Present day radio test systems are generally created by hard-wiring together various test elements such as signal generators, modulators, demodulators, I/O devices, amplifiers, mixers, coders and decoders (CODECs), amplifiers, detectors, spectrum analyzers, synthesizers, display devices, measuring devices, and so forth in a comparatively fixed configuration capable of testing a particular radio or radio system. When it is desired to test a different type of radio or radio system, the various sub-elements must be disassembled and reconnected in a new configuration adapted for the new radio or radio system.
Where it is desired that a single test set be able to handle multiple types of radios, the necessary test elements must be included and the various test elements made to be settable by panel switches or the like. As the number of different types of radios and radio systems increases, this classical approach to creating suitable test sets is no longer practical. Test sets made in this way are burdened by the requirement of having within the test set the capability to test all the envisioned radios even though most of the radio specific hardware stands idle much of the time. Such test sets become undesirably complex and expensive to build and operate and/or are undesirably time consuming to m-configure for different types of radios. Accordingly, there continues to be a need for an improved test system and method capable of accommodating a wide variety of modem radios and radio systems in a convenient and economic manner, and which may be easily and quickly re-configured for different types of radios.
For convenience of expression, the abbreviation "DUT" standing for "Device Under Test" is used to refer to the radio or radio system or sub-system intended to be tested. The words "radio test system" and "radio test set" are used interchangeably to refer to a means for testing radios or radio systems or sub systems or combinations thereof.